Smoky wrote the NASCAR rule book. Or at least he made them write it by finding loopholes as fast as they could fill them.
7/8 scale Chevelle (that gave us the famous templates)
Air vents behind rear glass in front of trunk lid ducting hi pressured air from under the car to low pressure drag area. Pull a little vacuum.
Bondo smooth under side, better flow out, less pressure under.
Gas tank roll cage. PanAm Linc racers had gas in doors.
Left rotating engine
Race car suspended too low, used 2x4" pieces for shims to meet regulation height, fell out at first bump.
Jim Hall of Chaparral fame was about the same. Everytime he came up with something truely unique, CanAm outlawed it. High rear wing, then the articulated wing linked to brakes, ground effect skirts that touched the ground and then moveable skirts. Then was the sucker car.
What ticked Hall off was CanAm was supposed to be an UN-LIMITED series.
Wings are still in, Porsche and a Jap car has an articulated one to match speed. Ground effect has been developed to the nth degree. Glass re-enforced plastic structural monocoque tub and auto trans big influence on today's racers design.
Everybody cheated a little, Ford's Talledaga (and Mercury clone) had the spot weld flange between underbody tray and outer body shell left oversized and untrimmed decreasing side body clearane by 1.75 to 2.0"
That help maintain the low pressure area under car at speed for ground effects.